1. Field of the Invention
The present invention relates to an optical system. More particularly, the present invention relates to a light source module and an optical projection system.
2. Description of Related Art
In recent years, the liquid crystal display technology is widely applied in our daily lives, such as liquid crystal televisions, notebook computers, the liquid crystal display (LCD) of desktop computers and liquid crystal projectors. Wherein, the liquid crystal projector is an important element for large-scale display technology. Most liquid crystal projectors apply liquid crystal panels with high resolution to enhance the display quality.
The conventional liquid crystal panel utilized in the liquid crystal projector is a liquid crystal display element formed on a glass substrate or a silicon substrate. Generally, the thin film transistor (TFT) or metal-oxide-semiconductor transistor (MOS transistors) is used as an active element in liquid crystal panels, and then the active element and the pixel electrode electrically coupled thereto drive the liquid crystals to perform the display function. With small volume and high resolution, the liquid crystal panel fittingly complies with the trend of a downsizing liquid crystal projector. In addition, the design of the optical projection system also determines the performance of the liquid crystal projector.
In the conventional reflective liquid crystal projector utilized in an optical projection system, the high-pressured mercury light source is usually adopted in the optical projection system as a light source. However, the optical characteristic of the high pressured mercury light source is that the intensity of green light is higher than that of red light, so in a white balance process, the driving voltage of the LCD panel corresponding to green light must be lowered to achieve the required white field. However, the control voltage has its range, so when the driving voltage of the LCD panel is lowered corresponding to the green light for white balance effect, the adjustment of gray level is limited.